1. Field of the Disclosure
The present disclosure relates generally to preventing or reducing treeing effects on media sheets imaged by electrophotographic imaging devices, and particularly to the use of end cap members associated with the backup roll of a fuser assembly for such imaging devices.
2. Description of the Related Art
Current belt fuser assemblies of electrophotographic imaging devices include a metal belt encasing a ceramic slab heater, and a backup roll having a silicone rubber layer and a smooth polyperfluoroalkoxy-tetrafluoroethylene (PFA) sleeve at least partly surrounding the rubber layer. In the fuser assembly, the backup roll and the belt with the heater are pressed together to form the fuser nip, which is the surface area that the media sheets contact and pass through in order to fuse a toner image on the sheet to the sheet itself. The metal belt may be a Teflon coated metal belt for monochrome imaging devices or a metal tube with a rubber layer and a PFA sleeve for color imaging devices.
“Treeing” is an effect that occurs when the sheet passes through the fuser nip and begins to corrugate and then eventually fold in on itself. Certain inconsistencies in the media sheet or printer design will cause the sheet to be compressed along its width such that wrinkles begin to form in the sheet. If these wrinkles become severe, treeing will occur. The result of treeing is that a crease is formed down the length of the media sheet that varies in length and depth.
Many known factors lead to treeing, the most common issues. For instance, treeing is more likely to occur when the media sheet is skewed as it enters the fuser nip, i.e., the leading edge of the sheet is not parallel with the fuser nip. Further, treeing is known to occur if the profile of the fuser nip is improperly designed or manufactured. Another factor that may cause treeing is the media sheet absorbed moisture from its environment, causing it to have a wavy edge and/or inconsistent width along the length of the sheet.
Accordingly, there is a need for an improved system for reducing or otherwise eliminating the occurrence of treeing in electrophotographic imaging devices.